The invention relates to a television camera comprising a preamplifier suitable for use with a pick-up tube incorporating an anti-comet tail gun. The preamplifier has an input terminal to which at least a control electrode of a transistor and a terminal of a resistor are connected, and an output terminal for supplying an amplified picture signal when the picture signal is applied from the pick-up tube to the input terminal of the preamplifier by a direct current connection.
Such a camera comprising a preamplifier is described in an article in the "Journal of the SMPTE", July 1973, pages 547 to 551, inclusive. The transistor, which comprises an insulated gate electrode, is arranged near the pick-up tube to which the gate electrode is connected by way of a control electrode. The drain or output electrode of this transistor and the adjacent resistor which form part of a first preamplifier stage, are connected to a remote second stage of the preamplifier by a multi-wire cable by way of direct current connection. This second stage comprises transistors which are suitable for a high supply voltage, for example equal to 50 V.
In the described preamplifier the high supply voltage of 50 V is used to enable processing of large signal current peaks occurring in the input signal. These signal current peaks occur in the early part of line blanking periods and are associated with pick-up tubes having an anti-comet tail gun. The current peaks are inherent to the anti-comet tail gun and are unavoidable. In order to prevent the preamplifier from being saturated at the limit of its signal range due to the current peaks, the preamplifier is overrated as regards the supply voltage (equal to 50 V). When a picture signal at the preamplifier output has a nominal range from 0 to, for example, 300 mV, which corresponds to a signal current from 0 to, for example 300 nA at the input terminal, current peaks may occur up to, for example, 50 .mu.A. When the above-mentioned high supply voltage is used no saturation of the preamplifier occurs.